Methods used in vehicles, such as automobiles, have been developed for acquiring information on people, other vehicles, obstacles, the road surface, and the like in the direction in which a vehicle is traveling. This information is then used for driving assistance, such as warning the driver to avoid a vehicle collision, braking automatically, or controlling the accelerator for cruise control.
Vehicle driving is affected by the state of the road surface on which the vehicle travels. For example, to drive the vehicle in the desired direction at the desired speed, the driver brakes and steers differently depending on the state of the road surface, such as whether the road surface is frozen, wet, or dry. Outputting information based on the state of the road surface to get the driver's attention and transmitting such information to an apparatus for supporting vehicle control are also useful for supporting safe driving.